480i in the context of SDTV

Standard-definition television (SDTV; also standard definition or SD) is a digital television system that uses a resolution that is not considered to be either high or enhanced definition. Standard refers to offering a similar resolution to the analog broadcast systems used when it was introduced.

Enhanced-definition television, or extended-definition television (EDTV) is a Consumer Electronics Association (CEA) marketing shorthand term for certain digital television (DTV) formats and devices. Specifically, this term defines an extension of the standard-definition television (SDTV) format that enables a clearer picture during high-motion scenes compared to previous iterations of SDTV, but not producing images as detailed as high-definition television (HDTV).

The term refers to devices capable of displaying 480-line or 576-line signals in progressive scan, commonly referred to as 480p (NTSC-HQ) and 576p (PAL-HQ/SECAM) respectively, as opposed to interlaced scanning, commonly referred to as 480i (NTSC) or 576i (PAL, SECAM). High-motion is optional for EDTV.